SWOMCD
SPC MCD 171743
FLZ000-172015-
MESOSCALE DISCUSSION 1992
NWS STORM PREDICTION CENTER NORMAN OK
1243 PM CDT WED AUG 17 2011
AREAS AFFECTED...FL PENINSULA
CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY
VALID 171743Z - 172015Z
A FEW STORMS COULD PRODUCE WET MICROBURSTS CAPABLE OF DMGG WIND
GUSTS...MAINLY ACROSS CNTRL AND ERN SECTIONS OF THE FL PENINSULA.
THE ISOLATED NATURE OF THE SVR THREAT AND LACK OF CONVECTIVE
ORGANIZATION WILL PRECLUDE THE NEED FOR A WW.
EARLY AFTERNOON SFC MESOANALYSIS AND VISIBLE SATELLITE IMAGES REVEAL
A FEW FEATURES FOR CONVECTIVE INITIATION BETWEEN 18Z AND 21Z:
1. AN AGGREGATE OUTFLOW / WEST COAST SEA BREEZE BOUNDARY LIES ESEWD
FROM 40 SW OCALA TO 30 SSW ORLANDO AND SWD TO 20 E FORT MYERS AND
SEWD TO 45 SW MIAMI. ONGOING CONVECTION WITHIN 15 NM EITHER SIDE OF
NRN PARTS OF THIS FEATURE WILL REACH AREAS FROM NEAR ORLANDO TOWARD
OCALA DURING THE NEXT COUPLE OF HOURS...WHILE ADDITIONAL CONVECTION
DEEPENS FROM INCIPIENT TOWERING CUMULUS GROWTH FARTHER SOUTH ALONG
THE BOUNDARY TOWARD AREAS SE OF NAPLES. INLAND HEATING BEHIND THE
ONGOING CONVECTION IS SUPPORTING THE DEVELOPMENT OF A SECONDARY SEA
BREEZE CIRCULATION FROM NEAR TAMPA TO SAINT PETERSBURG...WHICH COULD
ALSO FOCUS CONVECTION LATER THIS AFTERNOON.
2. THE EAST COAST SEA BREEZE CONTINUES TO INCREASE IN DEFINITION
FROM NEAR DAYTONA BEACH TOWARD MIAMI...WITH SFC OBS ALONG THE
COASTAL ZONE SUGGESTING A RECENT WIND SHIFT TO ONSHORE. SCATTERED
CONVECTION WILL LIKELY DEVELOP ALONG THIS BOUNDARY AS AMPLE
INSOLATION CONTRIBUTES TO BOUNDARY LAYER DESTABILIZATION.
3. A DIFFUSE FRONTAL BOUNDARY DRAPED ACROSS THE NRN FL PENINSULA AND
PENETRATING WELL INTO THE CNTRL GULF OF MEXICO SHOULD ALSO PROVIDE
SUFFICIENT SFC CONVERGENCE FOR TSTM INITIATION.
MODIFIED 12Z RAOBS ACROSS THE DISCUSSION AREA INDICATE THAT MLCAPE
VALUES HAVE ALREADY INCREASED TO 2500-3500 J/KG OWING TO SFC
TEMPERATURES HAVING CLIMBED INTO THE UPPER 80S TO LOWER 90S. THIS
WILL SUPPORT VIGOROUS CONVECTION...WITH DCAPE VALUES REACHING NEAR
1000 J/KG SUPPORTING WET MICROBURSTS WITH COLLAPSING CONVECTION.
THIS THREAT WILL BE ENHANCED BY WATER LOADING PROCESSES OWING TO PW
VALUES OF 1.8 TO 2.2 INCHES PER RAOBS AND GPS DATA.
HOWEVER...LOWER/MIDDLE-TROPOSPHERIC FLOW UNDER 15 KT PER AREA VWP
DATA WILL FAVOR VERY LITTLE CONVECTIVE ORGANIZATION...AND ANY
INSTANCES OF SVR THREAT WOULD BE HIGHLY SPORADIC.
..COHEN.. 08/17/2011
...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...
ATTN...WFO...MFL...MLB...TBW...JAX...TAE...
LAT...LON 25368079 25808139 26208173 26968222 27698251 28408258
29048262 29548324 30108333 30348265 30198157 29318093
28368054 27458020 25718016 25368079
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